Allright, this is strange and it freaks me out.
We had this thread some time ago, but it was kinda inconclusive.

www.oscarfishlover.com/oscar-fish-advice...28-oscar-gills#69342

Now my O is acting in the same way.

he's breathing through one side of his gills.
One side, the gill plate stay closed and the gills only show a tiny bit.
His other side gill plate is opened and i see the gills moving.
They even seem to be coming out a bit more than usual.
Now i checked the photo's from last night, but i can't see them there either.
I may have missed it before, but on the other hand, that's doubtfull.

waterparameters are at OFL standards, nitrates 10.
No change in diet, tankmates or maintenance.
Nor in feeding or other behaviour.
And here's a video:



as you can see the left side stays closed.
Now i could do with some encouragement!
The other thread said gillflukes???
Now what's this???

I have had the good luck through my health books and to be quite honest I cannot find anything that mentions an Oscar keeping its gill shut tightly. Any gill problems will result in the fish showing obvious signs of stress, normally gasping at the surface, breathing heavily, or remaining motionless. If all your water checks out on you haven't got any toxins present then it's a little difficult to try and pinpoint what, and if anything is indeed wrong. I would be inclined to monitor the situation and hope that everything improves, I don't think there's really anything you can do apart from keep an eye on the the water conditions & fish.

Your water definitely checks out?

Yes, i do my regular weekly 50% wc, add prime and my O's scars from the Vieja are healing fast .
Half his finspine has regenerated allready.
That's why i think it's odd.
I wonder if fish have a autonomous respons on their gills.
Like they could choose to hold it still...
I'm allways keeping close watch on the fish, but it could be that it's been that way for longer...

Not that I have ever seen them myself, but I believe GIll flukes will be visible to the naked eye if you carefully at the fish's gills, basically they are just parasites.

and they could effect only one side of the gills?
I read that gill flukes can get into the tank by feeders.
My frozen silversides???
I was just waiting for him to jawn and flush his gills, but he don't do it right now.
Oh well, i'll do some more investigating on those flukes.
See if i can recognize something.

Uhm, found something, but the symptoms don't match at all.

www.fishdeals.com/fish_diseases/skin_gill_flukes/
My fish ate good and was chasing the worms through the tank.
No heavier breathing.
No change in behaviour at all.
Now i hope to see him breathing normal again tomorrow.

thats very weird, maybe he hurt it or a parasite?

i just checked, my nightlights are on, but the gill plate was open again, and he's breathing through the gills again.
Strangely i noticed the other gill doing the same now.
My O seems to be using one gill after the other...
now that's a thing i hadn't noticed before.
now i have to study my O even more than i allready did.
man, i spook real easy when my fish are involved.

Glad things are improving Hun!

With other fish I've had, this usually means a minimal/nominal chlorine and or toxic presense.

the footage shows no problem at all...he/she swims very calmly and no stress sign at
all. i had seen an oscar with flukes and it keeps on shaking...breathing fast as
if she want to eject something.... in your case...there is no sign at all...
i wouldn't worry much if i were you....

when i turned off the livingroom lights and went to check on my O, i had to stick my nose to the glass.
My o got mad at me and did his blowing-up and acting mad thingy.
He totally opened both his gills to make himself look big!
That's my boy.
all seems fine and i only can conclude that an O does not use his gills simultaniously all the time.
If my fish was sick there should be some kind of behavioural change, so I'm not worrying anymore.